Jul 29, 2014 3:52 GMT
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Polar melting: UCI hosts global ice project planning meeting
Climate scientists from across the nation are gathering at UC Irvine this week to plan the next phase of an ambitious campaign: using planes to map the planet’s dwindling polar ice.
The prognosis is bad. Sea levels already are rising in part because of ice loss; the losses at both poles appear to be accelerating; and projections strongly suggest that it’s only going to get worse.
Sea levels could rise 12 inches or more by 2050, about half of that due to ice loss, recent projections show. Other estimates suggest a rise of as much as a few feet by 2100 — potentially inundating coastal communities built close to sea level.
Scientists at the UC Irvine conference say the rapid changes at both poles are likely a product of global warming. “The polar regions are very much influenced by climate change,” said NASA’s Bill Krabill, the principal investigator for topographical mapping on the project. “We’re bringing airplanes to bear on the problem.”
Mapping polar ice by plane is vital to fill a major gap in scientific knowledge otherwise left open by NASA budget constraints.
A satellite known as ICESat stopped collecting data on ice loss last year, then burned up as it fell into the atmosphere.
Funding to build ICEsat2 won’t be available until 2016.
Enter “Ice Bridge,” a six-year, $90 million effort to bridge the gap between the two satellites using measurements taken by plane. It is said to be the largest airborne survey of polar ice ever undertaken.
Ice Bridge scientists are meeting in UC Irvine’s Croul Hall this week to examine the latest data from the project and to plan its next phase.
Part of the reason they are gathering in Orange County, scientists at the conference said, are two of the stars in the polar ice firmament: Eric Rignot, who measures ice loss using radar, and Isabella Velicogna, who measures ice sheets using gravity measurements from space.
The two hold positions at both UC Irvine and the Jet Propulsion Laboratory in Pasadena.
“They are two of the top, top, top scientists doing this kind of work,” said Thomas Wagner, NASA program scientist for the ice-related projects. “This is the biggest thing happening in ice science right now.”
The planes of the Ice Bridge project fly repeatedly over both poles, taking a variety of measurements that can be combined to produce ultra-high resolution, three-dimensional mapping of polar ice.
The measurements include radar that can penetrate to bedrock beneath the ice, “lidar” that uses lasers to make exacting measurements of the ice surface, and gravitational sensors that can map water-covered parts of the sea floor inaccessible to radar.
Velicogna said she is working to marry the plane-based measurements with other sets of data, such as those from the twin Grace satellites, which can map the poles by detecting subtle changes in gravity as they pass overhead. That should provide a sharper picture of the changing polar landscape.
“The ice sheets are changing a lot, and we see now things that we would never have expected five years ago,” Velicogna said. “We have a good monitoring system, but there are still a lot of things we don’t understand.”
The scientists are reviewing new data on accelerating melting in Greenland, and planning their next attack on Antarctica.
They say the Antarctic continent is especially challenging for overflights because of its enormous size.
“Antarctica is seven times bigger, and it’s a very different climate,” Rignot said. “There are different sets of climate regimes within Antarctica.”
And while loss of ice is clearly measurable in west Antarctica, especially on the Antarctic peninsula, the vast ice sheets in east Antarctica are so far showing little change, he said.
Nailing down exactly how ice is changing at the poles is critical to refining and sharpening computer models of Earth’s changing climate.
“In both places, we want to see how the ice is changing,” Rignot said. “It’s a coupled system. You can’t just look at the ice sheet as an isolated system. The ice sheets are part of the global climate system. They interact with the ocean and the atmosphere."